The improved lock mechanism of the present invention arose out of the need to securely lock a plurality of parts of an injection mold together against the high pressure generated during injection and curing of a thermoplastic or similar material, which pressure can easily generate forces exceeding 25 tons. Further, there was a necessity to assure a positive and safe separation of the plural mold parts to enable retrieval of a molded product and to prevent an accidental and/or rapid closing of the mold onto the hands and/or hand held tool of any operator that may have become placed between the separated mold parts. Further, the present invention also arose out of a need to enable the mold parts to be placed into an unlocked condition prior to any mold opening process and by structure that would readily cooperate with different ones of the plural mold housing structures mounted on the same turntable.
It is now a known technique to mount a plurality of injection molds at spaced intervals about the periphery of a rotatable turntable. For example, such machines are disclosed in U.S. Pat. Nos. 4,111,623 and 4,424,015. Further, mechanisms for locking mold halves together are disclosed in U.S. Pat. Nos. 4,315,727 and 4,372,738. Each of the above-listed patents is currently owned by the assignee of the present invention. Although the locking mechanisms disclosed in U.S. Pat. Nos. 4,315,727 and 4,372,738 are very effective, they do require a rather complicated procedure to be followed when it is desired to remove an injection mold with one type of mold cavity configuration provided therein from the turntable and replace it with another one having a different mold cavity configuration therein. This becomes extremely important in situations where a single turntable may have a plurality of different injection molds mounted thereon, each injection mold having a different mold cavity configuration therein. If it is desired to replace one or more of the several injection molds mounted on the turntable, the whole system will be down for an inordinate period of time while the complicated procedure is being followed to facilitate a change in the injection molds.
Further, when the various ones of the injection molds are being replaced, care has to be exercised to make sure that the new mold so placed on the turntable will become properly aligned with the mold top lifting structure. Failure to properly align the new injection mold may result in the mold top being inadvertently dropped due to an inadequate engagement thereof with the top of the mold, as might occur through a use of the mold top lifting device shown in FIGS. 6 and 7 of U.S. Pat. No. 4,424,015.
Further, it is desirable to limit the spacing that will occur between the multiple parts of an injection mold, namely, an injection mold having, for example, three such parts. Use of such a mold would permit at least one component to be molded between the first and second mold parts while, and simultaneously therewith, a second component was being molded between the second and third parts. During an opening of the injection mold having plural mold parts, it is necessary to provide adequate spacing between the separated mold parts to enable an operator to reach in between the separated mold parts to remove therefrom the molded component. While various and separate structures could be provided for accommodating a control of each of the desired functions mentioned above, it is desirable to minimize the provision of supplemental structure to facilitate a manufacturer of such a control at a minimum of expense.
Accordingly, it is an object of the invention to provide a mold structure adapted to be mounted onto a turntable and have a capability of effecting an opening of the mold in a safe and secure manner.
It is a further object of this invention to provide a mold structure, as aforesaid, which has plural parts and structure for effecting a predetermined separation between the mold parts upon an opening of the mold structure.
It is as further object of the invention to provide a mold structure, as aforesaid, wherein the mold locking structure and the structure for effecting a separation between the plural components of a mold to a predetermined spacing are integrated into a compact arrangement.